Q. Find the least square number which is exactly divisible by each of the numbers : 8, 12, 15,and 20.
Find LCM: To find the least square number that is exactly divisible by 8, 12, 15, and 20, we first need to find the least common multiple (LCM) of these numbers. The LCM of a set of numbers is the smallest number that is a multiple of each of the numbers in the set.
Prime Factorization: We start by finding the prime factorization of each number.8=2312=22×315=3×520=22×5
Calculate LCM: Next, we take the highest powers of all prime factors found in the factorization of each number to find the LCM. LCM = 23×3×5 (since 23 is the highest power of 2, 3 is the highest power of 3, and 5 is the highest power of 5)
Ensure Square Number: Calculating the LCM gives us:LCM = 8×3×5=24×5=120
Make LCM Square: Now, we need to ensure that the LCM is a square number. A square number is an integer that is the square of another integer. If the LCM is not a square number, we need to multiply it by the smallest number necessary to make it a square.
Multiply by Factors: The prime factorization of the LCM 120 is 23×3×5. To make it a square, we need to have even powers of all prime factors. Currently, the powers of 2, 3, and 5 are not even.
Final Result: To make the LCM a square, we need to multiply it by another 2 (to make the power of 2 even), by 3 (to make the power of 3 even), and by 5 (to make the power of 5 even). This will give us the least square number.
Final Result: To make the LCM a square, we need to multiply it by another 2 (to make the power of 2 even), by 3 (to make the power of 3 even), and by 5 (to make the power of 5 even). This will give us the least square number.Multiplying the LCM by 2, 3, and 5 gives us:Least square number = LCM ×2×3×5=120×2×3×5=120×30=3600
Final Result: To make the LCM a square, we need to multiply it by another 2 (to make the power of 2 even), by 3 (to make the power of 3 even), and by 5 (to make the power of 5 even). This will give us the least square number.Multiplying the LCM by 2, 3, and 5 gives us:Least square number = LCM ×2×3×5=120×2×3×5=120×30=3600The prime factorization of 20 is 21, which is indeed a square number (22). Therefore, 20 is the least square number that is exactly divisible by 24, 25, 26, and 27.
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